Quantum well field effect transistors including group III and group V elements in channel regions may be used to improve device speed and to reduce power consumption because group III-V elements can have higher electron mobility than silicon. Quantum well field effect transistors may include delta doped layers that can contribute carriers to the channel regions.
Additionally, integrated circuit devices may need transistors with different threshold voltages. Accordingly, several technologies, including adjustment of channel doping concentrations and gate work functions, have been developed to implement transistors with different threshold voltages within one integrated circuit device. To adjust gate work functions, gate materials having different work functions and different channel materials may be used.